Scar Size Research Articles

Fibroblast-specific deletion of ERBB4 impairs cardiac regeneration in neonatal mice

Abstract Background Scarless regeneration of the neonatal mammalian heart is a remarkable but poorly understood process. Previous studies have shown that paracrine actions of neuregulin-1 (NRG1) are indispensable to stimulate cardiomyocyte proliferation in the injured neonatal heart, and are mediated by activation of the ERBB4 receptor. It remains unclear, however, whether NRG1 also contributes to other steps of neonatal cardiac regeneration, e.g. to the control of collagen synthesis by fibroblasts, hence contributing to scarless healing. Purpose To study temporal evolution of the infarct size during 21 days after myocardial infarction (MI) in neonatal fibroblast-specific Erbb4 knock-out (KO) and wild type (WT) mice. We hypothesized that scarless healing would be completed within 21 days in WT mice, and incomplete in KO mice. Methods Fibroblast-specific hemizygous Erbb4 KO (FB-Erbb4-KO) mice were generated (Erbb4F/+ Col1a2-Cre+, C57BL/6 background), because fibroblast-specific nullizygous Erbb4 KO were not viable. Validation of the KO was performed both on RNA (qPCR) and protein (western blot) level. MI was induced in one-day old FB-Erbb4-KO and WT littermates of both sexes by permanent ligation of the left anterior descending (LAD) coronary artery under hypothermic anaesthesia. Pups from both groups were euthanized at 4 (WT, n=9; KO, n=11), 7 (WT, n=12; KO, n=4), 10 (WT, n=11; KO, n=7) and 21 (WT, n=16; KO, n=8) days post-MI. Following dissection, hearts were formalin-fixed and paraffin embedded for histopathological evaluation. Transverse sections were cut at 4 distinct locations from the ligation site to the apex and stained with Masson’s Trichrome for infarct scar measurement. Genotyping was performed post-mortem and unblinded after data analysis. Results Both the transgenic mice model and the LAD ligation technique were successfully validated. No significant differences in the initial infarct scar size were observed between WT and FB-Erbb4-KO mice 4 days post-MI (p=0.6556). 7-days post-MI the infarct scar size was 6-fold smaller compared to 4 days post-MI in both FB-Erbb4-KO and WT mice, with a trend towards a larger infarct scar size in the FB-Erbb4-KO group compared to WT (p=0.0989). At day 10 post-MI, infarct scar size in the FB-Erbb4-KO group was significantly larger (p=0.0499) compared to WT. At 21 days post-MI, the infarct size had almost completely disappeared in the WT group, but remained clearly present in the FB-Erbb4-KO group (Fig. 1, p=0.0099). Infarct scar sizes at all timepoints are graphically shown in Fig. 2. Conclusion Fibroblast-specific deletion of the ERBB4 receptor causes incomplete resolution of the infarct scar in murine neonates 21 days after MI. While the initial infarct scar size 4 days after injury is the same, impaired scar resolution becomes progressively more evident towards day 21 post-MI. These findings indicate that scarless healing of the neonatal mammalian heart requires NRG1/ERBB4 signalling in fibroblasts.Fig. 1Fig. 2

Deep learning for quantification of myocardial scar and microvascular obstruction in late gadolinium enhancement cardiovascular magnetic resonance images

Abstract Objectives Detecting and measuring myocardial scar and microvascular obstruction (MVO) accurately following reperfusion therapy is clinically vital for patients with acute myocardial infarction (AMI). Current clinical practice relies on manual delineation of endocardial borders as well as hyper- and hypo-enhanced regions on late gadolinium enhancement (LGE) cardiovascular magnetic resonance (CMR) images for scar and MVO quantification, respectively. However, this approach is subjective, labor-intensive, and time-consuming. The objective of this study is to develop and assess a convolutional neural network (CNN)-based method for the automated quantification of LGE scar and MVO in AMI patients. Methods A total of 1836 LGE images from 252 patients with AMI were analyzed, with the cohort comprising 232 males and an average age of 56±9 years. Our approach, utilizing a combined architecture of cascaded YOLOv8 (You Only Look Once version 8) and nnU-Net, was implemented for the simultaneous segmentation of the left ventricular (LV) myocardium, scar, and MVO in LGE images. Independent datasets for training, validation, and testing were maintained in an 8:1:1 ratio. Performance evaluation was conducted by comparing the results to manual scar and MVO quantification, utilizing metrics such as the Dice similarity coefficient (DSC) and Bland-Altman analysis. Results The automated segmentation process took 0.05 seconds per image. The segmentation accuracy, as assessed by the DSC, yielded values of 0.96±0.04 (per-patient, n=25) and 0.96±0.05 (per-slice, n=184) for scar segmentation, and 0.86±0.17 (per-patient) and 0.89±0.15 (per-slice) for MVO segmentation. In per-patient analysis, the volumes of automatically segmented scar and MVO demonstrated strong agreement with manually derived results, with biases [limits of agreement] of -0.3 [-3.0, 2.4] cm³ and 0.1 [-0.2, 0.3] cm³, respectively. Furthermore, there was strong concordance between automatically and manually derived scar size as a percentage of LV mass (-0.2 [-3.1, 2.7] %) and MVO size as a percentage of scar (1.2 [-5.6, 8.0] %). Conclusions The findings demonstrate excellent agreement between our proposed automated deep-learning solution and clinical expert annotation, suggesting its potential as a predictive tool for prognosis and clinical outcomes in patients with AMI.

Molecular Scarring in Relapsing Psoriasis: Crosstalk of Keratinocytes and Immune Cells

Abstract Introduction/Objective Psoriasis is a chronic skin disorder with a tendency for relapse, characterized by immune- mediated mechanisms leading to papulosquamous lesions. Despite advances in treatment, many patients experience relapse, particularly in previously healed areas, referred to as “molecular scarring.” This scarring suggests a complex interaction between keratinocytes and immune cells, including tissue-resident memory T cells (TRMs), cytokines, and epigenetic modifications, contributing to the pattern-specific recurrence of psoriasis. Methods/Case Report After reviewing 31 articles on PubMed, we focused on the immunopathogenesis of psoriasis, examining the role of TRMs, the balance between regulatory T cells (Tregs) and Th17 cells, and the impact of various treatment modalities on disease recurrence. It evaluates the expression of TRM markers and the effectiveness of treatments such as anti-IL-17 agents and phototherapy in altering disease progression. The study also explores the genomic characteristics of psoriatic lesions post-treatment and the duration of clinical remission associated with different therapeutic approaches. Results (if a Case Study enter NA) The findings demonstrate a significant role of TRMs in psoriasis relapse, with environmental triggers reactivating these cells and leading to the production of inflammatory cytokines. Treatments targeting IL-17 showed a rapid decrease in TRM markers, particularly in the dermis, and were associated with different durations of disease remission based on the therapeutic approach. The study also found that the genomic profile of treated lesions does not fully normalize, with variations in gene expression linked to the type of treatment and possibly influencing the size of the molecular scar and relapse duration. Conclusion Psoriasis relapse is intricately linked to the presence of TRMs and the molecular scarring of previously healed lesions, influenced by various treatment modalities. The study underscores the importance of targeting TRMs and adjusting therapeutic strategies to extend the period of clinical remission and prevent the transition to more severe disease forms. Future research should focus on elucidating the detailed mechanisms of psoriasis relapse and developing targeted treatments to normalize the genomic profile of healed skin, ultimately improving patient outcomes and management of the disease.

Novel Fluorescence-Based Methods to Determine Infarct and Scar Size in Murine Models of Reperfused Myocardial Infarction.

Determination of infarct and scar size following myocardial infarction (MI) is commonly used to evaluate the efficacy of potential cardioprotective treatments in animal models. However, histological methods to determine morphological features in the infarcted heart have barely improved since implementation while still consuming large parts of the tissue and offering little options for parallel analyses. We aim to develop a new fluorescence technology for determining infarct area and area at risk that is comparable to 2,3,5-triphenyltetrazolium chloride (TTC) staining but allows for multiple analyses on the same heart tissue. For early and late time points following MI, we compared classical histochemical approaches with fluorescence staining methods. Reperfused MI was induced in male mice, the hearts were extracted 24 h, 7-, 21-, or 28-days later and fluorescently stained by combining Hoechst and phalloidin. This approach allowed for clear visualization of the infarct area, the area at ischemic risk and the remote area not affected by MI. The combined fluorescence staining correlated with the classic TTC/Evans Blue staining 24 h after MI (r = 0.8334). In later phases (>7 d) post-MI, wheat germ agglutinin (WGA) is equally accurate as classical Sirius Red (r = 0.9752), Masson's (r = 0.9920) and Gomori's Trichrome (r = 0.8082) staining for determination of scar size. Additionally, feasibility to co-localize fluorescence-stained immune cells in specific regions of the infarcted myocardium was demonstrated with this protocol. In conclusion, this new procedure for determination of post-MI infarct size is not inferior to classical TTC staining, yet provides substantial benefits, including the option for unbiased software-assisted analysis while sparing ample residual tissue for additional analyses. Overall, this enhances the data quality and reduces the required animal numbers consistent with the 3R concept of animal experimentation.

Evaluation of a Cosmetic Formulation Containing Arginine Glutamate in Patients with Burn Scars: A Pilot Study

Background: Patients with burn scars require effective treatments able to alleviate dry skin and persistent itching. Ion pairing has been employed in cosmetic formulations to enhance solubility in solvents and improve skin permeability. To evaluate the efficacy and safety of the cosmetic formula “RE:pair (arginine–glutamate ion pair)”, we analyzed scar size, itching and pain, skin barrier function, scar scale evaluation, and satisfaction in our study participants. Methods: A total of 10 patients were recruited, and the formula was used twice a day for up to 4 weeks. Results: Itching was significantly alleviated after 4 weeks of treatment (95% CI = −0.11–1.71) compared to before application (95% CI = 2.11–4.68). Transepidermal water loss (TEWL) showed an 11% improvement after 4 weeks (95% CI = 3.43–8.83) compared to before application (95% CI = 3.93–9.88), and skin coreneum hydration (SCH) showed a significant 41% improvement after 4 weeks (95% CI = 43.01–62.38) compared to before application (95% CI = 20.94–40.65). Conclusions: Based on the confirmation that RE:pair improves skin barrier function and relieves itching, it is likely to be used as a topical treatment for burn scars pending evaluation in follow-up studies (IRB no. HG2023-016).

In silico evaluation of cell therapy in acute versus chronic infarction: role of automaticity, heterogeneity and Purkinje in human

Human-based modelling and simulation offer an ideal testbed for novel medical therapies to guide experimental and clinical studies. Myocardial infarction (MI) is a common cause of heart failure and mortality, for which novel therapies are urgently needed. Although cell therapy offers promise, electrophysiological heterogeneity raises pro-arrhythmic safety concerns, where underlying complex spatio-temporal dynamics cannot be investigated experimentally. Here, after demonstrating credibility of the modelling and simulation framework, we investigate cell therapy in acute versus chronic MI and the role of cell heterogeneity, scar size and the Purkinje system. Simulations agreed with experimental and clinical recordings from ionic to ECG dynamics in acute and chronic infarction. Following cell delivery, spontaneous beats were facilitated by heterogeneity in cell populations, chronic MI due to tissue depolarisation and slow sinus rhythm. Subsequent re-entrant arrhythmias occurred, in some instances with Purkinje involvement and their susceptibility was enhanced by impaired Purkinje-myocardium coupling, large scars and acute infarction. We conclude that homogeneity in injected ventricular-like cell populations minimises their spontaneous beating, which is enhanced by chronic MI, whereas a healthy Purkinje-myocardium coupling is key to prevent subsequent re-entrant arrhythmias, particularly for large scars.

Microparticle Mediated Delivery of Apelin Improves Heart Function in Post Myocardial Infarction Mice.

Apelin is an endogenous prepropeptide that regulates cardiac homeostasis and various physiological processes. Intravenous injection has been shown to improve cardiac contractility in patients with heart failure. However, its short half-life prevents studying its impact on left ventricular remodeling in the long term. Here, we aim to study whether microparticle-mediated slow release of apelin improves heart function and left ventricular remodeling in mice with myocardial infarction (MI). A cardiac patch was fabricated by embedding apelin-containing microparticles in a fibrin gel scaffold. MI was induced via permanent ligation of the left anterior descending coronary artery in adult C57BL/6J mice followed by epicardial patch placement immediately after (acute MI) or 28 days (chronic MI) post-MI. Four groups were included in this study, namely sham, MI, MI plus empty microparticle-embedded patch treatment, and MI plus apelin-containing microparticle-embedded patch treatment. Cardiac function was assessed by transthoracic echocardiography. Cardiomyocyte morphology, apoptosis, and cardiac fibrosis were evaluated by histology. Cardioprotective pathways were determined by RNA sequencing, quantitative polymerase chain reaction, and Western blot. The level of endogenous apelin was largely reduced in the first 7 days after MI induction and it was normalized by day 28. Apelin-13 encapsulated in poly(lactic-co-glycolic acid) microparticles displayed a sustained release pattern for up to 28 days. Treatment with apelin-containing microparticle-embedded patch inhibited cardiac hypertrophy and reduced scar size in both acute and chronic MI models, which is associated with improved cardiac function. Data from cellular and molecular analyses showed that apelin inhibits the activation and proliferation of cardiac fibroblasts by preventing transforming growth factor-β-mediated activation of Smad2/3 (supporessor of mothers against decapentaplegic 2/3) and downstream profibrotic gene expression. Poly(lactic-co-glycolic acid) microparticles prolonged the apelin release time in the mouse hearts. Epicardial delivery of the apelin-containing microparticle-embedded patch protects mice from both acute and chronic MI-induced cardiac dysfunction, inhibits cardiac fibrosis, and improves left ventricular remodeling.

Association between in vitro susceptibility and clinical outcomes in fungal keratitis

PurposeThe purpose of this study was to assess the association between antifungal susceptibility as measured by minimum inhibitory concentration (MIC) and clinical outcomes in fungal keratitis.MethodsThis pre-specified secondary analysis of the Mycotic Ulcer Treatment Trial II (MUTT II) involved patients with filamentous fungal keratitis presenting to Aravind Eye Hospitals in South India. Antifungal susceptibility testing for natamycin and voriconazole was performed on all samples with positive fungal culture results according to Clinical and Laboratory Standards Institute Guidelines. The relationship between MIC and clinical outcomes of best-corrected visual acuity, infiltrate or scar size, corneal perforation, need for therapeutic penetrating keratoplasty, and time to re-epithelialization were assessed.ResultsWe obtained MIC values from 141 patients with fungal keratitis. The most commonly cultured organisms were Aspergillus (46.81%, n = 66) and Fusarium (44.68%, n = 63) species. Overall, there was no association between antifungal MICs and clinical outcomes. Subgroup analysis revealed that among Fusarium-positive cases, higher voriconazole MIC was correlated with worse three-month best-corrected visual acuity (p = 0.03), increased need for therapeutic penetrating keratoplasty (p = 0.04), and time to re-epithelialization (p = 0.03). No significant correlations were found among Aspergillus-positive cases. There were no significant correlations found between natamycin MIC and clinical outcomes among organism subgroups.ConclusionsDecreased susceptibility to voriconazole was associated with increased odds of requiring a therapeutic penetrating keratoplasty in Fusarium-positive cases. Susceptibility to natamycin was not associated with any of the measured outcomes.

A composite patch loaded with 2-Deoxy Glucose facilitates cardiac recovery after myocardial infarction via attenuating local inflammatory response

Local inflammatory microenvironment in the early stage of myocardial infarction (MI) severely impaired cardiac recovery post-MI. Macrophages play a pivotal role in this process. A classical glycolytic inhibitor, 2-Deoxy-Glucose (2-DG), has been found to regulate the excessive pro-inflammatory macrophage polarization in the infarcted myocardium. This study investigated the effect of 2-DG-loaded chitosan/gelatin composite patch on the infarct microenvironment post-MI and its impact on cardiac repair. The results showed that the 2-DG patch significantly inhibited the expression of inflammatory cytokines, alleviated reactive oxygen species (ROS) accumulation, repressed the proinflammatory polarization of macrophages, attenuated local inflammatory microenvironment in the ischemic hearts, as well as improved cardiac function, reduced scar size, and promoted angiogenesis post-MI. In terms of mechanism, 2-DG exerts anti-inflammatory effects through inhibiting the NF-κB signaling pathway and reducing the assembly and activation of the NLRP3 inflammasome. These findings suggest that 2-DG composite patch may represent a promising therapeutic strategy for cardiac repair after MI.

Predicting Late Gadolinium Enhancement of Acute Myocardial Infarction in Contrast-Free Cardiac Cine MRI Using Deep Generative Learning.

Late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) is a standard technique for diagnosing myocardial infarction (MI), which, however, poses risks due to gadolinium contrast usage. Techniques enabling MI assessment based on contrast-free CMR are desirable to overcome the limitations associated with contrast enhancement. We introduce a novel deep generative learning method, termed cine-generated enhancement (CGE), which transforms standard contrast-free cine CMR into LGE-equivalent images for MI assessment. CGE features with multislice spatiotemporal feature extractor, enhancement contrast modulation, and sophisticated loss function. Data from 430 patients with acute MI from 3 centers were collected. After image quality control, 1525 pairs (289 patients) of center I were used for training, and 293 slices (52 patients) of the same center were reserved for internal testing. The 40 patients (401 slices) of the other 2 centers were used for external testing. The CGE robustness was further tested in 20 normal subjects in a public cine CMR data set. CGE images were compared with LGE for image quality assessment and MI quantification regarding scar size and transmurality. The CGE method produced images of superior quality to LGE in both internal and external data sets. There was a significant (P<0.001) correlation between CGE and LGE measurements of scar size (Pearson correlation, 0.79/0.80; intraclass correlation coefficient, 0.79/0.77) and transmurality (Pearson correlation, 0.76/0.64; intraclass correlation coefficient, 0.76/0.63) in internal/external data set. Considering all data sets, CGE demonstrated high sensitivity (91.27%) and specificity (95.83%) in detecting scars. Realistic enhancement images were obtained for the normal subjects in the public data set without false positive subjects. CGE achieved superior image quality to LGE and accurate scar delineation in patients with acute MI of both internal and external data sets. CGE can significantly simplify the CMR examination, reducing scan times and risks associated with gadolinium-based contrasts, which are crucial for acute patients.

Efficacy of mesenchymal stem cell transplantation on major adverse cardiovascular events and cardiac function indices in patients with chronic heart failure: a meta-analysis of randomized controlled trials

BackgroundThe effects of mesenchymal stem cells (MSCs) on heart failure (HF) have been controversial. This study was conducted to investigate whether the transplantation of MSCs after HF could help improve clinical outcomes and myocardial performance indices.MethodsUsing a systematic approach, electronic databases were searched for randomized controlled trials (RCTs), which evaluated the transplantation of MSCs after HF. The outcomes owf interest included clinical outcomes and myocardial function indices. We also assessed the role of age, cause of heart failure, cell origin, cell number, type of donor (autologous/allogeneic), and route of cell delivery on these outcomes. Using the random-effects method, a relative risk (RR) or mean difference (MD) and their corresponding 95% confidence intervals (CI) were pooled.ResultsSeventeen RCTs including 1684 patients (927 and 757 patients in the intervention and control arms, respectively) were enrolled. The RR (95% CI) of mortality was 0.78 (0.62; 0.99, p = 0.04) in the MSC group compared to the controls. HF rehospitalization decreased in the MSC group (RR = 0.85 (0.71–1.01), p = 0.06), but this was only significant in those who received autologous MSCs (RR = 0.67 (0.49; 0.90), p = 0.008). LVEF was significantly increased among those who received MSC (MD = 3.38 (1.89; 4.87), p < 0.001). LVESV (MD = −9.14 (−13.25; −5.03), p < 0.001), LVEDV (MD = −8.34 −13.41; −3.27), p < 0.001), and scar size (standardized MD = -0.32 (-0.60; -0.05), p = 0.02) were significantly decreased. NYHA class (MD = −0.19 (−0.34; −0.06), p = 0.006), BNP level (standardized MD = −0.28 (−0.50; −0.06), p = 0.01), and MLHFQ (MD = −11.55 (−16.77; −6.33), p = 0.005) significantly decreased and 6-min walk test significantly improved (MD = 36.86 (11.22; 62.50), p = 0.001) in the MSC group. Trials were not affected by the participants’ etiology of heart failure, while trials with the autologous source of cells, MSC doses lower than 100 million cells, and intracoronary injection performed significantly better in some of the outcomes.ConclusionTransplantation of MSCs for ischemic or dilated heart failure patients may reduce all-cause mortality and improve clinical condition. Moreover, this treatment would improve left ventricular function indices and reduce scar size.Graphical

Intramyocardial immunomodulation with human CD16+ monocytes to treat myocardial infarction in pig: a blind randomized preclinical trial.

Human CD16+ monocytes (hCD16+ Ms) have proangiogenic properties. We assessed the feasibility, safety and efficacy of hCD16+ Ms in a porcine model of myocardial infarction (MI). A total of 27 female Large White pigs underwent MI with reperfusion and cardiac magnetic resonance (CMR). Five days later, animals received intramyocardial injections of hCD16+ Ms in saline (n = 13) or saline only (n = 14). hCD16+ Ms were selected from leucocyte cones. Feasibility/safety endpoints included injury at injected sites, malignant arrhythmias, cancer, haematoma, left ventricular (LV) dilatation, troponin release and downstream organ injury. Co-primary efficacy outcome included LV scar and ejection fraction (LVEF) at 30-day post-injections by CMR. Immunohistochemistry included neo-angiogenesis, fibrosis, markers of myofibroblast and inflammation. Four animals were excluded before injections due to untreatable malignant arrhythmias or lung injury. Median cell number and viability were 48.75 million and 87%, respectively. No feasibility/safety concerns were associated with the use of hCD16+ Ms. The LV scar dropped by 14.5gr (from 25.45 ± 8.24 to 10.8 ± 3.4 gr; -55%) and 6.4gr (from 18.83 ± 5.06 to 12.4 ± 3.9gr; -30%) in the hCD16+ Ms and control groups, respectively (p = 0.015). The 30-day LVEF did not differ between groups, but a prespecified sub-analysis within the hCD16+ Ms group showed that LVEF was 2.8% higher and LV scar 1.9gr lower in the subgroup receiving a higher cell dose. Higher tissue levels of neo-angiogenesis, myofibroblast and IL-6 and lower levels of TGF-β were observed in the hCD16+ Ms group. The use of hCD16+ Ms in acute MI is feasible, safe and associated with reduced LV scar size, increased tissue levels of neo-angiogenesis, myofibroblasts and IL-6 and reduced pro-fibrotic TGF-β at 30-day post-injections. A higher cell dose might increase the LVEF effect while reducing scar size, but this warrants validation in future studies.

Treating scars after burns with pulsed electric fields in the rat model.

Reducing scar size after severe burn injuries is an important and challenging medical, technology and social problem. We have developed a battery-powered pulsed electric field (PEF) device and surface needle electrode applicator to deliver pulsed electric fields to the healing dorsal burn wound in rats. PEF was used to treat residual burn wounds caused by metal contact in rats starting 10 days after the injury for 4 months every 11 or 22 days for 4 months using varying time applied voltages at 250-350V range, 400mA current, 40 pulses, 70 μs duration each, delivered at pulse repetition frequency 10 Hz at 5 locations inside the wound. We found 40-45% reduction in the scar size in comparison with untreated controls in both upper and lower dorsal locations on rats' backs two months after the last PEF application. We have not detected significant histopathological differences in the center of the scars besides the thickness of the newly generated epidermis, which was thicker in the PEF treated group.We showed that minimally invasively applied pulsed electric fields through needle electrodes are effective method and device for treating residual burn wounds in the rat model, reducing the size of the resulting scars, without any adverse reaction.

Abstract We115: Modified mRNA Therapeutics Inhibits Cardiomyocyte Apoptosis and Induces Cardiac Protection in Ischemic Heart Diseases

Introduction: Cardiovascular diseases are the leading cause of mortality worldwide. After myocardial infarction (MI), there is a permanent loss of cardiomyocytes (CMs), and as the mammalian heart has limited regenerative capacity, it leads to Heart Failure. Extracellular vesicles (EVs) derived from induced pluripotent stem cells (iPSCs) have emerged as potential therapeutic agents, yet their precise mechanism of CM survival and cardiac repair remains elusive. Hypothesis: The myocardial delivery of hiPSC-EV-specific protein improves cardiac function and mice survival post-MI by inhibiting CM apoptosis and oxidative stress molecular pathways. Methods and Results: Our preliminary studies confirmed that hiPSC-EVs promote CM survival post-MI in mice, and through proteomic analysis, we identified a novel protein uniquely expressed in hiPSC-EVs. We showed that the myocardial delivery of hiPSC-EVs specific protein in the form of modRNA inhibited CM apoptosis and induced CM survival post-MI. This increase in the CM's survival by hiPSC-EVs specific protein expression was associated with reduced scar size, improved cardiac function, and mice survival 28 days post-MI. Furthermore, using the siRNA and small molecule inhibition of hiPSC-EVs specific protein, we found enhanced MI-induced CM apoptosis post-MI. Mechanistic insights reveal the hiPSC-EVs specific protein induced STAT3 pathway, while STAT3 pathway inhibition by small molecule repressed hiPSC-EVs specific protein induced CM survival in vitro . Additionally, our preliminary study shows this protein translocates to the nucleus post-MI or ischemic injury. Conclusion: Taken together, the myocardial injection of hiPSC-EVs specific protein through a highly therapeutic modRNA tool improves cardiac function by inhibiting CMs apoptosis, and reactivating cardiac repair post-injury. Moreover, our studies demonstrate that the modRNA (protein) approach in mouse models is potentially adaptable for mRNA therapeutics in a clinical setup.

Abstract Mo040: Enhanced neovascularisation does not account for preservation of cardiac function by 11βHSD1 inhibition in a pig model of myocardial infarction

While acute post-myocardial infarction (MI) survival has improved thanks to early intervention, the myocardium still sustains damage that increases the risk of heart failure. Adrenal glucocorticoids (GCs) protect cardiomyocytes immediately after MI, but inhibition of GC regeneration within the heart by 11β-hydroxysteroid dehydrogenase 1 (11βHSD1) during infarct repair prevents subsequent deterioration of ventricular structure and function. In the 11βHSD1-knockout mouse this outcome is associated with enhancement of peri-infarct neovascularisation and prevention of infarct expansion. Here, we tested the hypothesis that pharmacological 11βHSD1 inhibition after MI can preserve function in a translational pig model and investigated the role of neovascularisation. MI was induced in female minipigs via temporary coronary occlusion. A standard clinical therapy (SCT, n =9) group received statin, anti-platelet, βadrenoreceptor antagonist and ACE inhibitor immediatley after MI, and a 11βHSD1i group (n=11) received SCT +11βHSD1 inhibitor (50mg/kg) from 48h after MI until the end of the study. Prior to 11βHSD1i treatment, short-axis cine and late gadolinium-enhanced MRI showed no difference in either infarct mass (4.2±0.4g SCT vs 4.0±0.6g 11βHSD1i) or ejection fraction (EF; 60.6±2.9% SCT vs 56.6±1.8% 11βHSD1i). However, by 28 days after MI, while EF was reduced in SCT pigs to 48±4%, it was maintained in pigs given additional 11βHSD1i treatment (57.9±1.8%, p &lt;0.05 vs SCT). Infarct mass did not differ between the two treatments, suggesting that inhibition of infarct expansion did not account for the improvement in function, this was confirmed by a similar area of infarct collagen in histological analysis. Angiogenesis, represented by an increase in CD31 +ve capillaries, was not enhanced in the infarct or the border zone (BZ) after 11βHSD1i treatment, relative to SCT. While vessel maturation (αSMA +ve vessels) was improved in the infarct compared to the remote myocardium, there was no difference between the two groups. Proteomic pathway analysis of the BZ indicated extracellular matrix organisation as the main pathway regulated by 11βHSD1i compared to SCT. In conclusion, 11βHSD1i after MI successfully preserves cardiac function and structure but the mechanism is independent of scar size reduction or enhanced neovascularisation. Instead, the beneficial effects of 11βHSD1i are likely to result from favourable regulation of collagen processing during scar formation.

Left Ventricular Unloading Using Intra-aortic Entrainment Pumping Before Reperfusion Reduces Post-AMI Infarct Size

BackgroundAnterior myocardial infarction standard of care prioritizes swift coronary reperfusion. Recent studies show left ventricular (LV) unloading with transvalvular axial flow pumps for 30 minutes before reperfusion (vs immediate reperfusion) decreases 28-day infarct size. Intra-aortic entrainment pumping, using hardware located away from the heart to provide support throughout the cardiac cycle, decreases effective systemic vascular resistance and augments visceral blood flow and pressure, and may reproduce this benefit with a decreased risk. This study characterized the hemodynamic effects of unloading before and during reperfusion using intra-aortic entrainment pumping and investigated whether unloading decreased anterior myocardial infarction scar size. Methods and ResultsYorkshire swine were subjected to 90 minutes of left anterior descending artery balloon occlusion and randomly assigned to immediate reperfusion (n = 6) vs 30 minutes unloading before reperfusion followed by 120 minutes of further unloading (n = 7). Unloading was achieved using percutaneous entrainment pumping in the descending aorta. The anterior myocardial infarction model matches that used in recent transvalvular pumping studies. Mortality before randomization was 22%. After randomization, mortality was 36% for immediate reperfusion and 0% for unloading. Unloading showed immediate hemodynamic benefit that increased through reperfusion and continued support, leading to distinct differences in cardiac function between groups after 30 minutes of reperfusion. Unloading increased stroke volume and cardiac efficiency at this timepoint relative to preocclusion baseline and reduced 28-day LV scar size by 37%–45%. ConclusionsWe present the first preclinical data showing extracardiac LV unloading before coronary reperfusion using intra-aortic entrainment pumping decreases 28-day infarct size. Extracardiac unloading to decrease LV scar size may provide an alternative to transvalvular pumping with potential advantages, including reduced risk.

Assessing four decades of fire behavior dynamics in the Cerrado biome (1985 to 2022)

BackgroundFire significantly transforms ecology and landscapes worldwide, impacting carbon cycling, species interactions, and ecosystem functions. In the Brazilian Cerrado, a fire-dependent savanna, the interaction between fire, society, and the environment is evident. Given that wildfires significantly contribute to greenhouse gas emissions, our study aimed to analyze four decades of burned area data to understand changes in fire dynamics, using Collection 2 of annual MapBiomas Fire maps (1985 to 2022). Our study examined spatiotemporal patterns, fire recurrence, fire distribution across land uses, temporal changes in fire scar size, burned area variations across ecoregions, and their correlation with farming areas.ResultsFrom 1985 to 2022, fire impacted 40% (792,204 km2) of the Cerrado biome, with 63% burning more than once. Natural vegetation was the most affected, primarily due to human-driven ignition during the dry season. A noticeable trend of later peaks in fire activity, concentrated towards the end of the dry season, along with an increase in patch size over time, characterized a clear shift in the Cerrado fire regime. Recently, the MATOPIBA region and the northern biome exhibited significant fire clusters, with burned areas rising alongside farming expansion. The ecoregion-based analysis identified fire hotspots, with the "Bananal" ecoregion, the largest wetland area in the biome, exhibiting increased fire recurrence and larger patch size over time.ConclusionsOur four-decade analysis of fire dynamics in the Cerrado revealed human-induced changes in the fire regime, originally shifting from July to September to a new fire season from August to October. This shift poses several environmental threats given their overlap with the driest months of the year. This study improved our understanding of changes in fire patterns and their impacts on each ecoregion and land use. Wetlands experienced the highest relative burned area, highlighting their ecological importance and increased vulnerability. In the southern Cerrado, where farming is established and natural vegetation more fragmented, fire events tend to decrease; while in the north, with recent farming expansion, fire susceptibility rises. Conservation-oriented strategies, like the Brazilian Integrated Fire Management (MIF), are crucial for mitigating impacts while enhancing the Cerrado’s resilience to climate change.

Interior shell patterns among the Spondylid species (Bivalvia: Spondylidae) in Mindanao, Philippines

Abstract. Ruaza FJC, Maturan DC, Bustillo E. 2024. Interior shell patterns among the Spondylid species (Bivalvia: Spondylidae) in Mindanao, Philippines. Biodiversitas 25: 2901-2906. The variations among the species of the Spondylus were assessed based on its interior shell pattern using landmark-based geometric morphometry. A total of 200 specimens were subjected to analysis. Samples of the Spondylid species were collected and photographed, and 15 landmarks from internal shell morphology were quantified and analyzed. The landmarks include the umbo, teeth, size of the muscle scar, and the pallial sinus. Multivariate analysis of variance revealed significant differences in internal shell characters among Spondylid species across sampling sites (p&lt;0.05). Canonical Variance Analysis (CVA) effectively differentiated the local Spondylid species into distinct clusters. In addition, the relative warps captured the most significant sources of variation in the morphological characters analyzed, leading to effective differentiation between the groups or populations of the species. The most distinguishing characteristics among the species are the distance of the pallial line to the ventral tip of the adductor muscle scar and the size of the cardinal tooth. The internal shell characters among the Spondylid species exhibit notable disparity despite their great morphological similarity. These shell characters can be used in the identification while conservation efforts are still in the initial stage of development. The presence of notable dissimilarities in the internal shell characteristics among the Spondylid species indicates that even slight deviations can result in noticeable morphological distinctions. This discovery enhances the understanding of the species divergence within this group and underscores the significance of incorporating internal shell characteristics into taxonomic and ecological investigations.

Ecological drivers of parrotfish coral predation vary across spatial scales

Parrotfishes (Labridae: Scarini) are widely recognized for their important functional role in reducing coral-algae competition by grazing algae, yet some species are also coral predators (corallivores) and thereby have direct negative impacts on corals they prey upon. To better understand the ecological drivers of parrotfish corallivory intensity, we compared patterns of relative predation scar size and abundance across spatial scales from individual coral colonies (&lt;1 to several meters in size), to reefs within islands (1 to 10s of km), to 4 regions across the Greater Caribbean (100s to 1000s of km) including Panamá, Florida, St. Croix, and Bonaire. Across reef sites, there was a positive correlation of both parrotfish density and biomass with the relative coral area preyed upon, but not predation scar abundance. While there was no apparent site-level effect of coral cover on corallivory intensity, we found that the abundance of colonies preyed upon was positively correlated with both coral diversity and the proportional cover of frequently targeted coral taxa within localized 30 m2 reef areas. At the scale of individual coral colonies, we found that while numerous coral taxa were preyed upon, corallivory was concentrated on a few species across regions, such as Orbicella spp., Porites spp., and Stephanocoenia intersepta. Our findings suggest that while increased parrotfish densities may result in an increased coral area preyed upon across reefs, corallivory intensity within reefs may decrease in response to declines in the cover of frequently targeted coral taxa and overall coral diversity.Spanish and Papiamentu versions of the abstract are provided in the Supplement at www.int-res.com/articles/suppl/m740p145_supp.pdf

Precision imaging of cardiac function and scar size in acute and chronic porcine myocardial infarction using ultrahigh-field MRI

Background7 T cardiac magnetic resonance imaging (MRI) studies may enable higher precision in clinical metrics like cardiac function, ventricular mass, and more. Higher precision may allow early detection of functional impairment and early evaluation of treatment responses in clinical practice and pre-clinical studies. Methods: Seven female German Landrace pigs were scanned prior to and at three time points (3–4 days, 7–10 days, and ~60 days) post myocardial infarction using a whole body 7 T system and three radiofrequency (RF) coils developed and built in-house to accompany animal growth. Results: The combination of dedicated RF hardware and 7 T MRI enables a longitudinal study in a pig model of acute and chronic infarction, providing consistent blood tissue contrast and high signal-to-noise ratio (SNR) in measurements of cardiac function, as well as low coefficients of variation (CoV) for ejection fraction (CoVintra-observer: 2%, CoVinter-observer: 3.8%) and infarct size (CoVintra-observer: 8.4%, CoVinter-observer: 3.8%), despite drastic animal growth. Conclusions: Best results are achieved via manual segmentation. We define state-of-the-art procedures for large animal studies at 7 T.